JP2017537497A - Reference signal design for wireless communication - Google Patents

Abstract

A reference signal design in wireless communication is disclosed. The base station may select a reference signal density scheme from a set of available density schemes associated with the port count. The reference signal density scheme may be selected based on the category of the mobile device that receives the reference signal transmission. The reference signal density scheme may be a relatively high density reference signal density scheme or a relatively low density reference signal density scheme, and the relatively high density reference signal density scheme may have more reference signals per subframe. Contains resource elements. The mobile device can determine a reference signal density scheme based on channel characteristics. A relatively dense reference signal density scheme may provide additional channel estimation opportunities for mobile devices. In some cases, the mobile device sends a channel estimated based on the received reference signal to the base station. [Selection] Figure 2

Description

Cross reference

  [0001] This patent application is filed on October 6, 2015, each assigned to the assignee of the present application, US Patent Application No. 14 by Chen et al., Entitled “Reference Signal Design for Wireless Communications”. No. / 876,678, and US Provisional Patent Application No. 62 / 061,634, filed October 8, 2014, entitled “Reference Signal Design for Wireless Communications” by Chen et al.

  [0002] The present disclosure relates to reference signal design for wireless communications, and more particularly for extended machine type communications in long term evolution wireless communications.

  [0003] Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and the like. These systems may be multiple access systems that can support communication with multiple users by sharing available system resources (eg, time, frequency, and power). Examples of such multiple access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems. .

  [0004] As an example, a wireless multiple-access communication system can include a number of base stations that each simultaneously support communication for multiple communication devices, sometimes known as user equipments (UEs). A base station may communicate with a UE on a downlink channel (eg, for transmission from the base station to the UE) and on an uplink channel (eg, for transmission from the UE to the base station). .

  [0005] The UEs are of different categories, including categories that have limited or reduced capabilities relative to other categories, such as configured to use reduced communication resources compared to other categories. It may be. The UE may operate in a restricted environment, such as underground, equipment closet, etc. The UE may also be limited by some narrow bandwidth operations. For example, machine type communication (MTC) devices may be affected by these things. However, some coverage enhancement (CE) techniques can provide additional operational flexibility to UEs such as MTC devices.

  [0006] The described features generally relate to one or more improved systems, methods, and / or apparatus for reference signal design in wireless communications. In general, a reference signal (RS) design can provide additional reference signals (RS) to certain types of UEs to allow for a denser RS scheme, eg, additional channel estimation feedback opportunities. In some examples, the base station determines that it is in communication with one type of UE or a UE operating in a category with reduced communication capabilities compared to other types of UEs or other categories. obtain. The base station can also determine the number of antenna ports available to the base station to send the RS to the UE. The base station then selects an RS according to an RS density scheme that provides sufficient opportunity for the UE to measure channel conditions and provide channel estimation feedback to ensure that coverage requirements are met, and the UE Can be sent to. The base station may receive channel estimation feedback from the UE and take appropriate steps to provide the necessary coverage based on channel conditions. In some examples, the base station may signal an indication of the RS density scheme used to the UE. In some examples, the base station may provide information about extended coverage for a particular transmission mode that may benefit from a commonly used RS density scheme or a denser RS density scheme than a less dense RS density scheme. A message including information indicating the request, etc. is received from the UE, and therefore an additional RS to be used can be configured.

  [0007] In one example, a method for wireless communication is described. The method may include selecting a reference signal (RS) density scheme from a set of RS density schemes and transmitting a reference signal to the mobile device according to the selected RS density scheme.

  [0008] In one example, an apparatus for wireless communication is described. The apparatus can include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions may be executable by the processor to select a reference signal (RS) density scheme from a set of RS density schemes and to transmit the reference signal to the mobile device according to the selected RS density scheme.

  [0009] In an example, an apparatus for wireless communication is described. The apparatus can include means for selecting a reference signal (RS) density scheme from a set of RS density schemes and means for transmitting a reference signal to the mobile device according to the selected RS density scheme.

  [0010] In one example, a non-transitory computer readable medium that stores computer executable code for wireless communication is described. The code may be executable by the processor to select a reference signal (RS) density scheme from the set of RS density schemes and to transmit the reference signal to the mobile device according to the determined RS density scheme.

  [0011] Some examples of methods, apparatus, or non-transitory computer readable media may include processes, features, means, or instructions for identifying a mobile device category or mobile device capability. Some examples of a method, apparatus, or non-transitory computer readable medium may include a process, feature, means, or instruction for identifying one or more parameters associated with a channel, where the parameters are In some examples, a mobile device port count may be included. Some examples of a method, apparatus, or non-transitory computer readable medium include an identified category of a mobile device, an identified capability of the mobile device, one or more parameters associated with a channel, or any of them May include a process, feature, means, or instruction for selecting an RS density scheme from a set of RS density schemes based at least in part on the combination.

  [0012] Some examples of methods, apparatus, or non-transitory computer readable media may include processes, features, means, or instructions for receiving channel quality indications from a mobile device. Is based at least in part on the transmitted reference signal. Transmitting the reference signal is a process, feature, means, or for transmitting at least one of a cell specific reference signal (CRS) or a demodulated reference signal (DM-RS), or a combination thereof, to the mobile device Instructions can be included. Some examples of methods, apparatus, or non-transitory computer readable media are processes for identifying a coverage extension for a mobile device and selecting an RS density scheme based at least in part on the identified coverage extension. , Features, means, or instructions.

  [0013] Some examples of a method, apparatus, or non-transitory computer readable medium identify a transmission mode for a mobile device and select an RS density scheme based at least in part on the identified transmission mode. Process, feature, means, or instruction. The transmission mode may include a broadcast mode or a unicast mode, and transmission may use a broadcast channel or a unicast channel. In some examples of the method, apparatus, or non-transitory computer readable medium, the transmission uses a control channel or data channel that may be a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH). Can do. Some examples of a method, apparatus, or non-transitory computer readable medium are processes for increasing the number of reference signals transmitted to a mobile device according to an RS density scheme, based on the identified category of the mobile device. It may include features, means, or instructions. The set of RS density schemes may include a relatively low density RS density scheme and a relatively high density RS density scheme. The mobile device category or mobile device capability is at least one of a machine type communication (MTC) device, a narrowband MTC device, user equipment (UE) operating in a narrowband, a UE that supports multiple RS density schemes, or Combinations thereof may be included. The category of the mobile device may be category 0. In some examples, mobile device capabilities may refer to the ability to operate in a mobile device category during a first time period, which may not be the same mobile device category as the second time period. Thus, in some examples, mobile device capabilities may refer to the possibility of being selectively configured to operate in categories based on various parameters.

  [0014] Some examples of methods, apparatus, or non-transitory computer-readable media may include a process, feature, means, or instructions for sending a message to a mobile device, where the message is an RS density scheme. With indications. The message may include an indication whether a cell specific reference signal (CRS) or a demodulated reference signal (DM-RS) or a combination thereof is included in the RS density scheme. In some examples of methods, apparatus, or non-transitory computer readable media, an indication of an RS density scheme may be transmitted in dedicated signaling or broadcast information. The port count may be at least one of 1 port or 2 ports. The RS density scheme may include 20 resource elements per subframe.

  [0015] In one example, a method for wireless communication is described. The method receives a reference signal transmitted according to a reference signal (RS) density scheme, and the RS density scheme is selected from a set of RS density schemes, the channel type or reference signal associated with the reference signal. Identifying an RS density scheme based at least in part on a coverage extension for a channel associated with the communication using a reference signal in accordance with the identified RS density scheme.

  [0016] In an example, an apparatus for wireless communication is described. The apparatus can include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions receive a reference signal transmitted by a processor according to a reference signal (RS) density scheme, wherein the RS density scheme is selected from a set of RS density schemes, a channel type or reference signal associated with the reference signal It may be feasible to identify an RS density scheme based at least in part on a coverage extension for a channel associated with and communicate using a reference signal according to the identified RS density scheme.

  [0017] In an example, an apparatus for wireless communication is described. The apparatus receives a reference signal transmitted according to a reference signal (RS) density scheme, wherein the RS density scheme is associated with a channel type or reference signal associated with the reference signal selected from a set of RS density schemes. Means may be included for identifying an RS density scheme based at least in part on the coverage extension for the identified channel and communicating using the reference signal in accordance with the identified RS density scheme.

  [0018] In one example, a non-transitory computer readable medium storing computer executable code for wireless communication is described. The code receives a reference signal transmitted by a processor according to a reference signal (RS) density scheme, wherein the RS density scheme is selected from a set of RS density schemes, or a channel type or reference signal associated with the reference signal It may be feasible to identify an RS density scheme based at least in part on a coverage extension for a channel associated with and communicate using a reference signal according to the identified RS density scheme.

  [0019] Some examples of methods, apparatus, or non-transitory computer readable media may include processes, features, means, or instructions for receiving an indication of an RS density scheme, where the RS density scheme is , Identified based at least in part on the indication, the indication being received in dedicated signaling or broadcast information. In some examples of a method, apparatus, or non-transitory computer readable medium, receiving a reference signal is at least one of a cell specific reference signal (CRS) or a demodulated reference signal (DM-RS), or A process, feature, means, or instruction for receiving the combination is provided.

  [0020] Some examples of methods, apparatus, or non-transitory computer-readable media are an increased number of reference signals according to an RS density scheme and based at least in part on a mobile device category or mobile device capability. It may include a process, feature, means, or instruction for receiving a set of reference signals. In some examples of methods, apparatus, or non-transitory computer readable media, mobile device categories include machine type communication (MTC) devices, narrowband MTC devices, UEs operating in narrowband, multiple RS density schemes. It comprises at least one of a supporting UE or a category 0 device.

  [0021] In some examples of a method, apparatus, or non-transitory computer readable medium, an RS density scheme is derived from a set of RS density schemes based at least in part on one or more parameters associated with the channel. The selected parameter may be associated with a port count of the mobile device in some examples.

  [0022] In some examples of a method, apparatus, or non-transitory computer readable medium, the type of channel comprises at least one of a broadcast channel or a unicast channel. In some examples of a method, apparatus, or non-transitory computer readable medium, the type of channel comprises at least one of a control channel or a data channel. In some examples, the channel type may be a physical downlink control channel (PDCCH) or a physical downlink shared channel (PDSCH).

  [0023] In some examples of a method, apparatus, or non-transitory computer readable medium, the channel coverage extension comprises channel repetition, and the RS density scheme is identified based at least in part on the number of channel repetitions. Is done. In some examples, an RS density scheme is identified for a first iteration number, another RS density scheme is identified for a second iteration number that is greater than the first iteration number, and another RS density scheme is: It has a higher RS density than the RS density scheme.

  [0024] In some examples of the method, apparatus, or non-transitory computer readable medium, communicating performs at least one of channel estimation or interference estimation using a reference signal, and channel estimation or A process, feature, means, or instruction for decoding a channel based on at least one of the interference estimates. In some examples of methods, apparatus, or non-transitory computer readable media, the RS density scheme comprises 20 resource elements per subframe.

  [0025] The foregoing has outlined rather broadly the features and technical advantages of the examples according to the present disclosure in order that the detailed description of the invention that follows may be better understood. Additional features and advantages are described below. The disclosed concepts and embodiments can be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein, as well as their manner of organization and operation, along with related advantages, will be better understood from the following description when considered in conjunction with the accompanying figures. Each of the figures is provided for purposes of illustration and description only and is not provided as a definition of the scope of the claims.

[0026] A further understanding of the nature and advantages of the present invention may be realized by reference to the following drawings and appendixes. In the appended figures, similar components or features may have the same reference label. In addition, various components of the same type can be distinguished by following the reference label with a dash and a second label that distinguishes between similar components. Where only the first reference label is used herein, the description applies to any one of similar components having the same first reference label, regardless of the second reference label. Is possible.
1 illustrates an example wireless communication system in accordance with aspects of the present disclosure. FIG. FIG. 7 is a message flow diagram illustrating aspects of reference signal design in wireless communications, in accordance with aspects of the present disclosure. FIG. 3 illustrates aspects of an exemplary reference signal density scheme according to aspects of the present disclosure. FIG. 3 illustrates aspects of an exemplary reference signal density scheme according to aspects of the present disclosure. FIG. 3 illustrates aspects of an exemplary reference signal density scheme according to aspects of the present disclosure. FIG. 3 illustrates aspects of an exemplary reference signal density scheme according to aspects of the present disclosure. FIG. 3 illustrates aspects of an exemplary reference signal density scheme according to aspects of the present disclosure. FIG. 7 is a message flow diagram illustrating aspects of reference signal design in wireless communications, in accordance with aspects of the present disclosure. FIG. 7 is a message flow diagram illustrating aspects of reference signal design in wireless communications, in accordance with aspects of the present disclosure. 1 is a block diagram of a device configured for use in wireless communications in accordance with aspects of the present disclosure. 1 is a block diagram of a device configured for use in wireless communications in accordance with aspects of the present disclosure. 1 illustrates a system for use in wireless communications in accordance with aspects of the present disclosure. FIG. 1 is a block diagram of an apparatus for use in wireless communications in accordance with aspects of the present disclosure. 1 is a block diagram of an apparatus for use in wireless communications in accordance with aspects of the present disclosure. 1 is a block diagram of a base station (eg, a base station that forms part or all of an eNB) for use in wireless communications, in accordance with aspects of the present disclosure. 6 is a flowchart illustrating an example method for wireless communication in accordance with aspects of the present disclosure. 6 is a flowchart illustrating an example method for wireless communication in accordance with aspects of the present disclosure. 6 is a flowchart illustrating an example method for wireless communication in accordance with aspects of the present disclosure.

  [0041] A wireless communication system may be configured to support device operation in a wider system bandwidth and with coverage enhancement (CE) for coverage limited devices. System extensions can allow devices that may be designed to operate in narrow bandwidths to operate effectively in wider bandwidths. For example, the system extension causes a device configured for operation in a 1.4 MHz bandwidth (eg, 6 resource blocks (RBs)) to operate in, eg, a 3, 5, 10, 15, or 20 MHz band. be able to. Such an extension may also allow a coverage extension on the order of 15 dB.

  [0042] In some examples, one or more devices of a wireless communication system may be a machine type communication (MTC) device or may be otherwise operating in the MTC category. . For example, the device may be configured to operate as a category 5 device during certain time periods and to operate as an MTC device during different time periods. In some cases, the system may use a broadband carrier (eg, 3-20 MHz). Multiple MTC devices may communicate simultaneously on the control and downlink channels in the wideband. For example, each MTC device can be monitored, transmitted, or received at any given time, subject to the constraints of 6 physical RBs (PRBs), with different MTC devices having different 6 Can be serviced with a PRB block. In other words, multiple MTC devices may communicate via frequency division multiplexing (FDM) resources of a single transmission time interval (TTI) (eg, subframe).

  [0043] To support system extension, the MTC control or data channel may be frequency division multiplexed with the control or data channel for other UEs, which may be MTC devices. These MTC control and data channels may be referred to as an MTC physical downlink control channel (MPDCCH) and an MTC physical downlink shared channel (MPDSCH), respectively. In some examples, an MTC device capable of such FDM operation may be referred to as an enhanced or evolved MTC (eMTC) device.

  [0044] MPDCCH and MPDSCH may operate consistently or beneficially with enhanced / developed PDCCH (EPDCCH), which may provide uplink and downlink grants to other UEs. For example, MPDCCH or MPDSCH with EPDCCH may be frequency division multiplexed in a single TTI. In some examples, the EPDCCH is implemented in dependence on the demodulation reference signal (DM-RS) as opposed to the cell specific reference signal (CRS), whereby the EPDCCH may be configured UE specific. Could be possible. That is, each UE in the cell may be configured to monitor a different set of resources and thus different EPDCCH. Extended or evolved MTC devices may be similarly configured to monitor MPDCCH or MPDSCH, or both.

  [0045] To support such extensions, the reference signal for the control or data channel, or both, is relative to other systems, such as a relatively early Long Term Evolution (LTE) system. Can be modified. These extensions may provide a reference signal that yields some desirable properties for various devices, such as MTC devices or eMTC devices. For example, a reference signal in an enhanced system may provide both broadcast (eg, MTC system information) and unicast transmission. They can also support coverage extensions including TTI bundling and non-bundling scenarios. Furthermore, they can support both normal and extended cyclic prefix (CP) implementations. Also, in view of the need for backward compatibility and flexible deployment, they can support both legacy and new carrier types (eg, LTE in unlicensed spectrum).

  [0046] An eMTC device can operate beneficially with knowledge of system expansion and some aspects of reference signal design, and these aspects can be communicated to the eMTC in broadcast information. For example, an eMTC device may use an antenna port (eg, a CRS port) used by a base station by decoding a physical broadcast channel (PBCH) and, in some examples, determining a CRS frequency shift. The number of can be determined. Further, the eMTC device can determine the system bandwidth (eg, for a wideband carrier) by decoding the PBCH.

  [0047] In some examples, the reference signal for an eMTC device may be based on, for example, a CRS resource element (RE) in a 6PRB band that is assigned to and monitored by a group of eMTC devices. The reference signal may also be based on the DM-RS RE in the assigned PRB. However, the DM-RS may be transmitted in all of the six allocated PRBs, in a subset, or not in any of them, depending on the PRB allocation. In some examples, the reference signal may be based on a combination of CRS RE and DM-RS RE.

  [0048] Various RS density schemes using different combinations of CRS and DM-RS RE may be utilized to facilitate eMTC operation. For example, an eMTC device may benefit from a higher density RS transmission than a commonly used RS density scheme or otherwise a relatively low density RS density scheme, It includes a set of CRS and DM-RS REs in a given PRB, which may be an increased number of reference signals, which may provide additional channel condition measurements and feedback opportunities. Additionally or alternatively, a higher density RS density scheme may allow MPDCCH or MPDSCH operation.

  [0049] According to aspects of this disclosure, a base station may select an RS density scheme to be used for a particular category of UEs or UEs operating in a different manner in a particular category. For example, a UE may have mobile device capabilities that refer to the possibility of being selectively configured to operate in categories based on various parameters. The RS density scheme may also be based on one or more parameters associated with the channel. In some examples, the RS density scheme may be based on the number of antenna ports used to transmit the RS to the UE.

  [0050] The RS density scheme increases the number of resource elements (REs) used for reference signal transmission within the PRB for some UEs or port counts, thus the UE measures the channel conditions. May provide additional opportunities for reporting. Channel states include signal phase, signal amplitude, signal strength, signal interference, signal distortion, signal-to-noise ratio (SNR), signal-to-interference plus noise ratio (SINR), signal-to-noise plus distortion ratio (SNDR), channel coefficient, etc. However, the present invention is not limited to these. In some aspects, the RS density scheme is at least in a coverage extension for the UE (eg, 15 dB coverage improvement), in a transmission mode for the UE (eg, unicast transmission, broadcast transmission, etc.), and the like. Can be based in part. In some examples, the added REs (eg, increased RS density) may be power ramped, eg, some REs may be transmitted with greater power than other REs.

  [0051] The following description provides examples and is not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made in the function and configuration of the elements described without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Also, features described in connection with some examples may be combined in other examples.

  [0052] FIG. 1 illustrates an example wireless communication system 100 in accordance with aspects of the present disclosure. The wireless communication system 100 includes a base station 105, a UE 115, and a core network 130. The core network 130 may provide user authentication, access authorization, tracking, Internet protocol (IP) connectivity, and other access functions, routing functions, or mobility functions. Base station 105 may interface with core network 130 through backhaul link 132 (e.g., S1) to implement radio configuration and scheduling for communication with UE 115, or a base station controller (not shown). Can operate under control. In various examples, base stations 105 communicate directly or indirectly (eg, through core network 130) with each other via backhaul link 134 (eg, X1 etc.), which can be a wired or wireless communication link. obtain.

  [0053] Base station 105 may wirelessly communicate with UE 115 via one or more base station antennas. Each of the base station 105 sites may provide communication coverage for a respective geographic coverage area 110. In some examples, base station 105 may be a transceiver base station, a radio base station, an access point, a radio transceiver, a Node B, an eNode B (eNB), a Home Node B, a Home eNode B, or some other suitable Sometimes called terminology. The geographic coverage area 110 for the base station 105 may be divided into sectors (not shown) that form part of the coverage area. The wireless communication system 100 may include different types of base stations 105 (eg, macro cell base stations and / or small cell base stations). Base station 105 may be configured to communicate using one or more communication technologies, and each communication technology may have an associated geographic coverage area 110. The geographic coverage area 110 for the first communication technology may overlap with the geographic coverage area 110 for the second communication technology, and the first and second communication technologies may be the same base station 105 or different bases. It can be associated with the station 105.

  [0054] In some examples, the wireless communication system 100 is an LTE / LTE-A network. In LTE / LTE-A networks, the terms evolved Node B or Extended Node B (eNB) may generally be used to describe the base station 105. The wireless communication system 100 may be a heterogeneous LTE / LTE-A network in which different types of eNBs provide coverage for various geographic regions. For example, each eNB or base station 105 may provide communication coverage for macro cells, small cells, and / or other types of cells. The term “cell” can be used to represent a base station, a carrier or component carrier associated with the base station, or a coverage area (eg, a sector, etc.) of the carrier or base station, depending on the context. ) Terms.

  [0055] A macrocell may generally cover a relatively large geographic area (eg, a few kilometers in radius) and may allow unrestricted access by UEs subscribed to service with a network provider. A small cell is a low power base station that may operate in the same or different (eg, licensed, unlicensed, etc.) frequency band as compared to a macrocell. Small cells may include pico cells, femto cells, and micro cells, according to various examples. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs subscribed to network provider services. A femtocell may also cover a relatively small geographic area (eg, home) and UEs that have an association with the femtocell (eg, UEs in a limited subscriber group (CSG), for users in the home) Limited access by a UE etc.). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, pico eNB, femto eNB or home eNB. An eNB may support one or more (eg, 2, 3, 4, etc.) cells (eg, component carriers).

  [0056] The wireless communication system 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timings, and transmissions from different base stations may not be time aligned. The techniques described herein may be used for either synchronous or asynchronous operations.

  [0057] A communication network that may accommodate some of the various disclosed examples may be a packet-based network that operates according to a layered protocol stack. In the user plane, communication at the bearer or packet data convergence protocol (PDCP) layer may be IP based. The radio link control (RLC) layer may perform packet segmentation and reassembly for communication over logical channels. The medium access control (MAC) layer can perform priority processing and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid ARQ (HARQ) to perform retransmissions at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer establishes, configures and maintains an RRC connection between the UE 115 and the base station 105 or core network 130 that supports radio bearers for user plane data. obtain. At the physical (PHY) layer, transport channels can be mapped to physical channels.

  [0058] The UEs 115 may be distributed throughout the wireless communication system 100, and each UE 115 may be fixed or mobile. UE 115 is a mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, A remote terminal, handset, user agent, mobile client, client, or some other suitable term may be included or so called by those skilled in the art. UE 115 may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, and so on. UE 115 may be a machine type communication (MTC) device, an extended or evolved MTC (eMTC) device, or the like, which may include automated instruments, sensors, etc. that may have relatively low throughput applications, etc. It may be operating in other ways. A UE may be able to communicate with various types of base stations and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.

  [0059] In some examples, UE 115 is an MTC or eMTC device located in an area that prohibits communication with base station 105. The MTC may be placed, for example, in a basement or equipment cabinet that may limit the likelihood that the MTC device will effectively receive transmissions from the base station 105. Base station 105 can therefore utilize coverage enhancement (CE) techniques to improve or increase the likelihood of successful communication with MTC devices. Coverage extension techniques may include several transmission strategies that increase the effective transmit power of the signal.

  [0060] As an example, CE techniques may include repetitive transmission, TTI bundling, HARQ retransmission, physical uplink shared channel (PUSCH) hopping, beamforming, power enhancement, or other techniques. The CE technique used may depend on the specific demands of the device in different situations. For example, TTI bundling may involve sending multiple copies of the same information in successive groups of TTIs rather than waiting for a negative acknowledgment (NACK) before retransmitting the redundancy version. This may be useful for users involved in VoLTE or Voice over IP (VOIP) communication. In other cases, the number of HARQ retransmissions may also be increased. Uplink data transmissions may be transmitted using frequency hopping to achieve frequency diversity. Beamforming may be used to increase the signal strength in a particular direction, or the transmit power need only be increased. In some cases, one or more CE options may be combined, and the CE level may be defined based on the number of decibels that the technique is expected to improve the signal (eg, no CE, 5 dB CE 10 dB CE, 15 dB CE, etc.). Additionally or alternatively, the coverage extension technique may include the selection of a higher density RS density scheme.

  [0061] The communication link 125 shown in the wireless communication system 100 may include an uplink (UL) transmission from the UE 115 to the base station 105 and / or a downlink (DL) transmission from the base station 105 to the UE 115. Downlink transmissions are sometimes referred to as forward link transmissions, and uplink transmissions are sometimes referred to as reverse link transmissions. Each communication link 125 may include one or more carriers, each carrier being a signal composed of multiple subcarriers (eg, waveform signals of different frequencies) modulated according to the various radio technologies described above. Good. Each modulated signal may be sent on a different subcarrier and may carry control information (eg, reference signal, control channel, etc.), overhead information, user data, etc. The communication link 125 uses two-way communication using frequency division duplex (FDD) (eg, using anti-spectral resources) or time division duplex (TDD) operations (eg, using unpaired spectral resources). Can be sent. A frame structure for FDD (eg, frame structure type 1) and a frame structure for TDD (eg, frame structure type 2) may be defined.

  [0062] In some examples of the wireless communication system 100, the base station 105 or UE 115 may employ an antenna diversity scheme to improve communication quality and reliability between the base station 105 and the UE 115. Multiple antennas may be included. Additionally or alternatively, the base station 105 and / or UE 115 uses multiple input multiple output (MIMO) techniques that can utilize a multipath environment to transmit multiple spatial layers carrying the same or different coded data. obtain.

  [0063] The wireless communication system 100 may support an operation on multiple cells or carriers, ie, a feature that may be referred to as carrier aggregation (CA) or multi-carrier operation. A carrier may be called a component carrier (CC), a layer, a channel, or the like. The terms “carrier”, “component carrier”, “cell”, and “channel” may be used interchangeably herein. The UE 115 may be configured with multiple downlink CCs and one or multiple uplink CCs for carrier aggregation. Carrier aggregation may be used with both FDD component carriers and TDD component carriers.

  [0064] In some examples, the base station 105 may select an RS density scheme from a set of available RS density schemes. In some examples, the selection of the RS density scheme may be based on the number of available antenna ports used to transmit the RS as well as the mobile device category or mobile device capability of the UE 115 to which the RS is being transmitted. For some categories or capabilities of UE 115, the base station may select an increase in the density of RSs transmitted in the PRB to provide additional channel measurements, interference measurements, and estimation support. For example, UE 115 may be an eMTC that uses increased RS density in the PRB to make additional RS measurements to provide clearer and clearer feedback information about channel conditions. Accordingly, the base station 105 may have more information on which transmission characteristics determination should be based, eg, modulation and coding scheme (MCS), throughput capability, data rate, transmission power, and so on. Thus, base station 105 adjusts the RS density scheme to provide additional channel measurements and reporting opportunities to support UE 115 associated with a particular category or otherwise operating in that category. Can do. In some examples, the base station 105 may send a message to the UE 115 indicating the selected RS density scheme. Base station 105 may, for example, transmit downlink control information (DCI) elements in the control channel, and DCI may indicate a particular RS density scheme.

  [0065] FIG. 2 shows a message flow diagram 200 illustrating aspects of reference signal design in wireless communications in accordance with aspects of the present disclosure. Message flow diagram 200 may illustrate aspects of wireless communication system 100 described with reference to FIG. Message flow diagram 200 includes a source cell 205 and a mobile device 210. The source cell 205 may be an example of one or more of the base stations 105 described with reference to FIG. The mobile device 210 may be an example of one or more of the UEs 115 described with reference to FIG. In general, message flow diagram 200 illustrates aspects of implementing a reference signal density scheme design in a wireless communication system. In some examples, a system device such as UE 115 or one of base stations 105 described with reference to FIG. 1 may be configured to perform some or all of the functions described below. A set of code for controlling may be executed.

  [0066] At block 215, the source cell 205 may identify a mobile device category or mobile device capability of the mobile device 210. In various examples, mobile device 210 may be associated with an identified category or otherwise operating in that category. For example, mobile device 210 may have mobile device capabilities that refer to the possibility of being selectively configured to operate in categories based on various parameters. In some examples, the mobile device category or mobile device capability may have reduced communication resources, such as reduced data rate, reduced bandwidth, than otherwise available via source cell 205. Or the like may relate to the configuration of the mobile device 210 for use. The mobile device 210 may be a low cost UE, MTC device, eMTC device, or the like. Additionally or alternatively, the mobile device category or mobile device capability for mobile device 210 can be from a coverage extension, from a communication configuration selected to support a particular transmission mode, to the mobile device 210 that may benefit from others. Can be associated.

  [0067] At block 220, the source cell 205 may identify one or more parameters associated with the channel. For example, the source cell 205 may identify the number of antenna ports, or simply “ports,” available to the source cell 205 for RS transmission on the channel. In various examples, the source cell 205 may have one port, two ports, three ports, etc. that can be used to transmit RSs to the mobile device 210. The port count may be determined based at least in part on the configuration of the source cell 205, the available (or free) ports of the source cell 205, and the like. In some examples, the mobile device 210 can be aware of the port count for the source cell 205, for example, by decoding the physical broadcast channel (PBCH) and the associated RS frequency shift. Additionally or alternatively, the mobile device 210 can be aware of the supported system bandwidth of the source cell 205 by decoding the PBCH.

  [0068] At block 225, the source cell 205 may select an RS density scheme from a set of RS density schemes available for RS transmission. In some examples, the selection of the RS density scheme may be based at least in part on parameters associated with the channel, and in addition or alternatively, at least in part on the mobile device category or mobile device capabilities of mobile device 210. In some examples, the selected RS density scheme may provide additional instances of RSs (eg, REs) within a given PRB. The RS transmitted according to the selected RS density scheme may include a cell specific reference signal (CRS), a demodulation reference signal (DM-RS) that may be referred to as a UE specific reference signal, or a combination thereof.

  [0069] In some aspects, the selected RS density scheme may support broadcast transmission, unicast transmission, or both. For example, an MTC system information block (SIB) may provide an indication of a selected RS density scheme. The selected RS density scheme may support transmission time interval (TTI) bundling as well as non-bundling for TTI. The selected RS density scheme may support standard length CP as well as extended length CP. In some examples, the selected RS density scheme may support heterogeneous networks, eg, LTE systems that use licensed or unlicensed spectrum.

  [0070] At 230, the source cell 205 may optionally send a signal that includes an indication of the selected RS density scheme to the mobile device 210, which may be sent by dedicated signaling or broadcast transmission. For example, the source cell 205 may send a DCI element over the control channel to inform the mobile device 210 of the selected RS density scheme. Alternatively, the source cell 205 may not send some or all of the indications of the selected RS density scheme to the mobile device 210. Instead, the mobile device 210 attempts to monitor the RE associated with the RS transmission and, if successful, the RS is targeted for channel measurement or interference measurement, i.e., with an RS according to the selected RS density scheme. You just have to decide. As an example, the mobile device 210 attempts to blindly decode the RS using cyclic redundancy check (CRC), and if the CRC is successful, the RS targets channel estimation and measurement according to the selected RS density scheme. You may decide that you are doing.

  [0071] At 235, the source cell 205 may send an RS to the mobile device 210 according to the selected RS density scheme. In various examples, the source cell 205 may send CRS, DM-RS, or a combination thereof in the PRB / subframe resource elements defined by the RS density scheme.

  [0072] FIGS. 3A-3E show diagrams 300-a-300-e illustrating aspects of an exemplary RS density scheme, respectively, according to aspects of the present disclosure. Chart 300 may illustrate aspects of wireless communication system 100 described with reference to FIG. One or more of the base stations 105 described above with respect to FIG. 1 or FIG. For example, the chart 300 can collectively represent a set of RS density schemes, where any one or more of the RS density schemes, in some examples, by port count, mobile device category, or mobile device capability. There may be associated with any one or more of the parameters associated with the channel. The base station 105 may select one of the RS density schemes for RS transmission to the UE 115. In some examples, a system device, such as UE 115 or one of base stations 105, may perform some or all of the functions shown with respect to diagram 300 described with reference to FIGS. 3A-3E. A set of code for controlling the functional elements may be executed.

  [0073] The example RS density scheme shown in chart 300 is generally represented in a subframe that includes two PRBs, eg, each PRB is identified as 12 subcarriers (tone indexes 0-11). And seven symbols (identified as symbol indices 0-6 and 7-13, respectively, for two PRBs). Thus, each PRB includes 84 resource elements (REs) (7 symbols multiplied by 12 subcarriers), and a subframe includes a total of 168 REs available for data or control information transmission. Base station 105 may transmit RSs in several REs depending on the particular RS density scheme for channel estimation or interference measurements at the UE. As previously discussed, parameters associated with the channel, such as a port count for base station 105, may be used to determine the number or location of REs for RS transmission, at least to some extent.

  [0074] For example, and as shown in FIG. 3A, the RS density scheme shown in chart 300-a may be associated with 1-port RS transmissions, associated with any category, or another method in any category. May be selected for an RS density scheme applicable to UE 115 operating in In some examples, the RS density scheme shown in chart 300-a may be referred to as a lower density RS density scheme. As shown in FIG. 3A, the base station 105 receives a one-port antenna (antenna port “antenna port” during RE corresponding to tone indexes 0, 3, 6, and 9 and symbol indexes 0, 4, 7, and 11, respectively. 16 RSs (8 RSs per PRB) can be transmitted over (identified as 0). That is, until 16 RSs are transmitted, base station 105 transmits an RS at tone index 0 and symbol index 0, another RS at tone index 3 and symbol index 0, and so on. In some aspects, the RS density scheme shown in chart 300-a may be a UE 115 associated with a mobile device category or mobile device capability, eg, an MTC or other that communicates using the full capability of the associated base station 105. May be applicable to the device. Accordingly, the base station 105 can avoid overhead signaling of the indication of the RS density scheme to the UE 115 in some aspects.

  [0075] As another example, and as shown in FIG. 3B, the RS density scheme shown in chart 300-b may also be associated with one-port RS transmissions, associated with several categories, or those categories. May be selected for an RS density scheme that is advantageous for UE 115 operating in a different manner. The RS density scheme shown in chart 300-b may be at least a higher density RS scheme as compared to the lower density RS density scheme shown in chart 300-a. In some examples, the RS density scheme shown in chart 300-b may be associated with a predefined mobile device category or mobile device capability, or otherwise operate in UE 115, eg, a narrowband UE, The base station 105 may select based on communication with an MTC device, eMTC device, or the like. In some aspects, the category of UE 115 associated with the communication and RS density scheme may correspond to lower functional requirements, eg, narrowband, low data rate, etc. In other words, the UE category may indicate to the base station the UE's capabilities for UL and DL communication. In general, the RS density scheme shown in diagram 300-b includes, for example, additional RSs per PRB or subframe compared to the RS density scheme shown in FIG. 3A. As shown in FIG. 3B, the base station may perform RS (eg, for symbol index 8 and tone indexes 0, 3, 6, and 9 for a total of 20 REs (or 20 instances of RS) per subframe , RE) may be sent. Accordingly, UE 115 may have four additional channel measurements, estimates, and reporting opportunities for the subframe.

  [0076] In some examples, the RS transmitted in the lower density RS density scheme of Chart 300-a may be a CRS and transmitted in the higher density RS density scheme shown in Chart 300-b. The surplus RE to be performed may be CRS, DM-RS, or a combination thereof. In some examples, the RE may be scheduled for DM-RS transmission, where the DM-RS signal may be used for channel estimation, similar to CRS transmission. Therefore, transmission of CRS type RS in DM-RS RE may increase RS design considerations. Additionally or alternatively, the base station 105 may transmit a DM-RS in the added RE. The DM-RS RE may be coded using a known precoder or may not be precoded. A UE 115 receiving a DM-RS may perform various combinatorial functions for determining channel estimation, such as weighting, averaging, and the like. For example, UE 115 uses CRS RE to measure channel condition, then performs DM-RS RE channel measurement or interference measurement, and based on both measurement sets, channel condition for channel estimation or interference estimation report The index of can be determined.

  [0077] In some examples, the selection of DM-RS REs for use in the RS density scheme may be based on UE 115 coverage requirements. For example, UEs 115 that do not require enhanced coverage for base station 105 may be scheduled to receive CRS REs. As another example, the DM-RS RE may be selected for inclusion in the RS density scheme based on the transmission mode of the UE 115, eg, the DM-RS RE may improve channel estimation or interference estimation reporting. , May be associated with other DM-RS REs. In other examples, the selection of DM-RS REs to be included in the RS density scheme is the same for control channels or data channels, eg, physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH). Or may be different.

  [0078] Referring to FIGS. 3C and 3D, an example RS density scheme for two-port RS transmission is shown in accordance with various aspects of the present disclosure. In general, the RS density scheme shown in chart 300-c may be a lower density RS density scheme, selected for UE 115 associated with any category or otherwise operating in any category. Often, the RS density scheme shown in diagram 300-d may be a higher density RS density scheme, associated with a particular category or operating in another manner in that category, eg, a reduced UE 115. It may be selected for eMTC devices that use communication resources. Base station 105 may transmit the RS via two antenna ports (identified as ports “0” and “1”) according to the selected RS density scheme. The RS density scheme shown in chart 300-c may include 16 REs transmitted in a subframe. In contrast, the RS density scheme shown in diagram 300-d may include four additional REs being transmitted for a total of 20 RS REs. This provides an additional opportunity for UE 115 operating in a particular category to measure and report channel conditions, which can be used to improve coverage for UE 115.

  [0079] In some cases, the higher density RS density schemes shown in diagrams 300-b and 300-d are backward compatible. For example, the higher density RS density schemes of charts 300-b and 300-d include RSs being transmitted according to the lower density RS density schemes of charts 300-a and 300-c, respectively. . Thus, for example, a UE 115 that does not support a higher density RS density scheme may still be able to perform a channel estimation or interference estimation procedure based on the known location of the RS. A UE 115 that supports the RS density scheme of the present disclosure may, however, use the additional REs of the RS density scheme shown in diagrams 300-b and 300-d for added channel measurements, interference measurements, and reporting opportunities. It may be possible.

  [0080] As another example, and as shown in FIG. 3E, 4-port RS transmission may be utilized in accordance with various aspects of the present disclosure. In some examples, the RS density scheme shown in chart 300-e may be selected for UE 115 associated with any category or operating in any manner in any category. Base station 105 may transmit 24 instances of RS in the RE associated with tone indexes 0, 3, 6, and 9 and symbol indexes 0, 1, 4, 7, 8, and 11. . Base station 105 may transmit 24 RSs using four antenna ports (identified as ports “0”, “1”, “2”, and “3”). Thus, UE 115 may have sufficient opportunities for channel estimation and reporting.

  [0081] FIG. 4 shows a message flow diagram 400 illustrating aspects of reference signal design in wireless communications, according to aspects of this disclosure. Message flow diagram 400 may illustrate aspects of wireless communication system 100 described with reference to FIG. Message flow diagram 400 includes a source cell 405 and a mobile device 410. The source cell 405 may be an example of an aspect of one or more of the base station 105 described with reference to FIG. 1 or FIG. 3 or the source cell 205 described with reference to FIG. The mobile device 410 may be an example of an aspect of one or more of the UE 115 described above with reference to FIG. 1 or FIG. 3 or the mobile device 210 described with reference to FIG. In general, message flow diagram 400 illustrates aspects of implementing a reference signal density scheme design in a wireless communication system. In some examples, a system device such as UE 115 or base station 105 described with reference to FIG. 1 or FIG. 3 or one of source cell 205 or mobile device 210 described with reference to FIG. A set of code for controlling the functional elements of the device can be executed to implement some or all of the functions described below.

  [0082] At block 415, the source cell 405 may identify a mobile device category or mobile device capability of the mobile device 410. In some examples, the categories may include reduced communication resources, such as reduced data rate, reduced bandwidth, etc., than otherwise available via source cell 405, e.g., eMTC device. It may relate to the configuration of mobile device 410 for use. Additionally or alternatively, the mobile device category or mobile device capability for mobile device 410 can be from a coverage extension, from a communication configuration selected to support a particular transmission mode, to the mobile device 410 that may benefit from others. Can be associated.

  [0083] At block 420, the source cell 405 may identify parameters associated with the channel. For example, in some examples, the source cell 405 can identify the number of ports available to the source cell 405 for RS transmission. In various examples, the source cell 405 may have one port, two ports, three ports, etc. available to send RSs to the mobile device 410. The port count may be determined based at least in part on the configuration of the source cell 405, the available (or free) port of the source cell 405, and the like. In some examples, the mobile device 410 can be aware of the port count for the source cell 405, for example, by decoding the physical broadcast channel (PBCH) and the associated RS frequency shift. Additionally or alternatively, the mobile device 410 can be aware of the supported system bandwidth of the source cell 405 by decoding the PBCH.

  [0084] At block 425, the source cell 405 may select an RS density scheme, eg, any one of the RS density schemes shown in the chart 300, from a set of RS density schemes available for RS transmission. it can. For example, the RS density scheme may be based at least in part on the port count of the source cell 405, and in addition or alternatively, the mobile device category or mobile device capability of the mobile device 410, or the mobile device 410 is another method therein May be based at least in part on the category operating at. In some examples, the RS density scheme may provide additional RSs within a given PRB, eg, the RS density scheme shown in charts 300-b or 300-d. The RS transmitted according to the selected RS density scheme may include a cell specific reference signal (CRS), a demodulation reference signal (DM-RS) that may be referred to as a UE specific reference signal, or a combination thereof.

  [0085] In some aspects, the RS density scheme may support both broadcast and unicast transmissions. For example, an MTC system information block (SIB) may provide an indication of the RS density scheme. The RS density scheme may support TTI bundling as well as non-bundling for TTI. The RS density scheme may support standard length cyclic prefix (CP) as well as extended length CP. In some examples, the RS density scheme may support heterogeneous networks, eg, LTE systems that use licensed or unlicensed spectrum.

  [0086] At 430, the source cell 405 may send a signal that includes an indication of the selected RS density scheme to the mobile device 410, which may be sent in dedicated signaling or broadcast transmissions. For example, the source cell 405 may send a DCI element over the control channel to inform the mobile device 410 of the selected RS density scheme. In some examples, the source cell 405 may also send an indication of whether DM-RS RE is being used in the selected RS density scheme by the DCI element. However, the mobile device 410 can determine aspects of the selected RS density scheme based on the available port count and / or knowledge of its category, for example, by decoding the PBCH.

  [0087] At 435, the source cell 405 may send an RS to the mobile device 410 according to the selected RS density scheme. In various examples, the source cell 405 may send CRS, DM-RS, or a combination thereof in the PRB / subframe RE defined by the RS density scheme.

  [0088] At block 440, the mobile device 410 may determine at least one of a channel estimate or an interference estimate for the transmitted RS RE. For example, the mobile device 410 can determine various channel state parameters, such as signal to noise ratio, signal to interference noise ratio, etc., based on measurements of RS transmitted according to a selected RS density scheme. In some examples where the RS density scheme includes CRS and DM-RS, the mobile device 410 may perform various combinatorial functions to determine channel estimation or interference estimation.

  [0089] At 445, the mobile device 410 may send a message to the source cell 405 that includes an indication of channel measurement and estimation or interference measurement and estimation. In examples where a higher density RS density scheme with additional REs is selected, channel estimation or interference estimation reporting may provide improved and / or more accurate channel state determination. Thus, the source cell 405 has improved information regarding channel conditions, and thus can make more informed decisions regarding MCS selection, throughput capability, data rate, transmit power, etc.

  [0090] FIG. 5 shows a message flow diagram 500 illustrating aspects of reference signal design in wireless communications in accordance with aspects of the present disclosure. Message flow diagram 500 may illustrate aspects of wireless communication system 100 described with reference to FIG. Message flow diagram 500 includes a source cell 505 and a mobile device 510. The source cell 505 is an example of an aspect of one or more of the base station 105 described with reference to FIG. 1 or FIG. 3 or the source cell 205 or 405 described with reference to FIG. possible. Mobile device 510 may be an example of an aspect of one or more of UE 115 described with reference to FIG. 1 or FIG. 3 or mobile device 210 or 410 described with reference to FIG. . In general, message flow diagram 500 illustrates aspects of implementing a reference signal density scheme design in a wireless communication system. In some examples, a system device such as UE 115, base station 105, source cell 205 or 405, or one of mobile devices 210 or 410 may perform some or all of the functions described below. A set of code for controlling the functional elements of the device may be executed.

  [0091] At 515, the source cell 505 may send a signal to the mobile device 510 that includes an indication of the RS density scheme selected from the set of RS density schemes. The RS density scheme may be selected based at least in part on any one or more of mobile device categories or mobile device capabilities of mobile device 510, or one or more parameters associated with the channel; The parameter may relate to the port count of the source cell 505 in some examples. For example, the source cell 505 may send a DCI element over the control channel to inform the mobile device 510 of the selected RS density scheme. In some examples, the source cell 505 may also send an indication of whether DM-RS RE is being used in the selected RS density scheme by the DCI element.

  [0092] At 520, the source cell 505 may send an RS to the mobile device 510 in accordance with the selected RS density scheme. In various examples, the source cell 505 may send CRS, DM-RS, or a combination thereof in the PRB / subframe RE defined by the RS density scheme.

  [0093] At block 525, the mobile device 510 may determine at least one of a channel estimate or an interference estimate for the transmitted RS RE. For example, the mobile device 510 may determine various channel conditions or interference conditions, eg, signal to noise ratio, signal to interference noise ratio, etc. based on measurements of RS transmitted according to the selected RS density scheme. it can. In some examples where the RS density scheme includes CRS and DM-RS, the mobile device 510 may perform various combinatorial functions to determine channel estimation or interference estimation.

  [0094] At 530, the mobile device 510 may send a message to the source cell 505 that includes indications of channel measurements and estimates. In examples where a higher density RS density scheme with additional REs is selected, the channel estimation report may provide improved and / or more accurate channel state determination. Thus, the source cell 505 has improved information regarding channel conditions, and thus can make more informed decisions regarding MCS selection, throughput capability, data rate, transmit power, and the like.

  [0095] FIG. 6 shows a block diagram 600 of a device 605 configured for use in wireless communications, in accordance with aspects of the present disclosure. Device 605 may be one or more of UE 115 described with reference to FIG. 1 or FIG. 3 or mobile devices 210, 410, or 510 described with reference to FIG. 2, FIG. 4, or FIG. 5, respectively. Can be an example of an embodiment. Device 605 may include a receiver module 610, a channel / interference estimation module 615, and a transmitter module 620. Device 605 may also be or include a processor (not shown). Each of these modules may be in communication with each other.

  [0096] The components of device 605 may individually use one or more application specific integrated circuits (ASICs) adapted to perform some or all of the functions applicable in hardware. Or it can be implemented collectively. Additionally or alternatively, the functions may be performed by one or more other processing units (or cores) on one or more integrated circuits. In other examples, other types of integrated circuits (eg, structured / platform ASICs, field programmable gate arrays (FPGAs), and other semi-custom ICs) that can be programmed in any manner known in the art. Can be used. The functionality of each module may be implemented in whole or in part using instructions embedded in memory formatted to be executed by one or more general purpose or application specific processors.

  [0097] The receiver module 610 may receive information such as packets, user data, or control information associated with various information channels (eg, control channels, data channels, etc.). Receiver module 610 may be configured to receive an indication of RS density scheme from base station 105 in addition to receiving RSs transmitted according to the RS density scheme. The information may be received in dedicated signaling or broadcast transmissions and may include one or more of CRS or DM-RS, or combinations thereof. Information may be passed to channel / interference estimation module 615 and to other components of device 605.

  [0098] Channel / interference estimation module 615 may determine a channel quality indication based on the reception and measurement of the RS and transmit the channel quality indication to base station 105. Channel / interference estimation module 615 may receive an indication of the RS density scheme selected for use by device 605 from base station 105 via receiver module 610. In some examples, the channel / interference estimation module 615 can identify an RS density scheme based at least in part on one of the type of channel coverage or the coverage extension for the channel.

  [0099] In some examples, the RS density scheme is based at least in part on the mobile device category or mobile device capability of the device 605, for example, whether or not the device 605 is an MTC device or an eMTC device. May be selected by the base station 105 based on operating as another device in another manner. Additionally or alternatively, the RS density scheme may be selected by the base station 105 based at least in part on one or more parameters associated with the channel, and the parameters in some examples may include the base station 105 Port counts, e.g., associated with antenna ports available to the base station 105 for RS transmission. Accordingly, the channel / interference estimation module 615 may receive an RS transmitted according to the indicated RS density scheme and perform channel measurements based on the RS. Channel / interference estimation module 615 may then pass an indication of at least one of channel estimation or interference estimation to transmitter module 620 for transmission to base station 105.

  [0100] In some examples, to provide additional RS RE to device 605, for example, to provide more opportunities for channel / interference estimation module 615 to measure and report current channel conditions. A higher density RS density scheme may be selected. Thus, the base station has improved information regarding channel conditions and thus can make more informed decisions regarding MCS selection, throughput capability, data rate, transmit power, etc.

  [0101] The transmitter module 620 may transmit one or more signals received from other components of the device 605. Transmitter module 620 may transmit an indication of channel estimation information to base station 105. In some examples, the transmitter module 620 may be collocated with the receiver module 610 within the transceiver module.

  [0102] FIG. 7 shows a block diagram 700 of a device 605-a configured for use in wireless communications, in accordance with aspects of the present disclosure. Device 605 was described with reference to UE 115 described with reference to FIG. 1 or FIG. 3, mobile device 210, 410, or 510 described with reference to FIG. 2, FIG. 4, or FIG. One or more of device 605 may be an example of an aspect. Device 605-a can include a receiver module 610-a, a channel / interference estimation module 615-a, and a transmitter module 620-a, which are examples of corresponding modules of device 605. It can be. Device 605-a may also include a processor (not shown). Each of these components may be in communication with each other. The channel / interference estimation module 615-a may include an RS density scheme determination module 705, a channel / interference estimation determination module 710, and a coverage extension / transmission mode module 715. Receiver module 610-a and transmitter module 620-a may each perform the functions of receiver module 610 and transmitter module 620 described with reference to FIG.

  [0103] The RS density scheme determination module 705 receives, via the receiver module 610-a, one or more messages including an indication of the RS density scheme selected by the base station 105, eg, DCI in the control channel. Elements may be received from base station 105. The RS density scheme determination module 705 determines, based on the indication, which REs in the PRB, PRB group, subframe, subframe group, or combinations thereof may include an RS for channel estimation. be able to. In some examples, the RS density scheme determination module 705 may identify an RS density scheme based at least in part on one of the channel type or coverage extension for the channel. In some examples, the channel type may include at least one of a broadcast channel or a unicast channel. In some examples, the type of channel can include at least one of control data or a data channel, and the data channel can be PDCCH or PDSCH in some examples. In some RS density schemes, the additional RS RE supports at least one of the mobile device category of device 605-a, the mobile device capability of device 605-a, or one or more parameters of the channel. And may be allocated for at least one of a channel estimation measurement or an interference estimation measurement, and the parameters may be related to a port count for the base station 105, etc., in some examples. Additionally or alternatively, the message may include an indication of whether the selected RS density scheme may include CRS, DM-RS, or a combination thereof.

  [0104] The channel / interference estimation determination module 710 cooperates with the receiver module 610-a or the RS density scheme determination module 705 to receive the RS in the RE associated with the RS density scheme and determine the channel state. What is necessary is just to measure RS in order to do. For example, the channel / interference estimation determination module 710 may determine an interference level, received signal strength, etc. to identify the channel operating state for one or more of the channels. In the case where the indicated RS density scheme includes DM-RS, channel / interference estimation determination module 710 may employ various combined functionality for determining channel estimation or interference estimation for CRS and DM-RS transmissions, eg, Weighting, averaging, etc. may be performed. In some aspects, DM-RS may be included in an RS density scheme to provide enhanced channel measurement and estimation or enhanced interference measurement and estimation.

  [0105] The coverage extension / transmission mode module 715 may determine whether one or more of coverage extension or a particular transmission mode is applicable for the device 605-a. For example, device 605-a may be an MTC device, a narrowband MTC device, a narrowband UE, a category 0 UE, etc., or otherwise operating in a different manner, with reduced communication requirements, For example, it may be associated with reduced data rate, limited data transmission, lower bandwidth, etc. Thus, device 605-a may be of a mobile device category or mobile device capability that can benefit from coverage enhancement from base station 105. In another example, device 605-a may wish to use a transmission mode that may benefit from additional channel estimation or interference estimation measurements and reports, eg, a broadcast transmission that may be a bursty transmission. is there. Accordingly, the coverage extension / transmission mode module 715 may send a signal indicating its category and / or requirement to the base station 105. The base station 105 may select an RS density scheme that considers the category / capability / necessity of the device 605-a and thus select an RS density scheme that provides sufficient channel estimation or interference estimation opportunities.

  [0106] FIG. 8 illustrates a system 800 for use in wireless communications in accordance with aspects of the present disclosure. System 800 may include UE 115-a, which may be UE 115 described with reference to FIG. 1 or FIG. 3, mobile device 210, 410 described with reference to FIG. 2, FIG. 4, and FIG. 510, or one or more of the devices 605 described with reference to FIGS. 6 and 7 may be examples of aspects.

  [0107] UE 115-a may generally include components for two-way voice and / or data communication including a component for transmitting communication and a component for receiving communication. UE 115-a may include one or more antennas 840, a transceiver module 835, a processor module 805, and a memory 815 (including code 820), each of which (eg, one or more). (Via bus 845) may communicate with each other directly or indirectly. The transceiver module 835 is configured to communicate bi-directionally with one or more networks via one or more antennas 840 or one or more wired or wireless links, as described above. obtain. For example, the transceiver module 835 may include any of the base stations 105 described with reference to FIGS. 1 and 3 and any of the source cells 205, 405, or 505 described with reference to FIGS. One or more may be configured to communicate bidirectionally. Transceiver module 835 modulates a packet, provides the modulated packet to one or more antennas 840 for transmission, and a modem configured to demodulate packets received from one or more antennas 840 Can be included. UE 115-a may have one or more antennas 840 capable of transmitting and / or receiving multiple wireless transmissions simultaneously. The transceiver module 835 may be capable of communicating simultaneously with one or more base stations 105 via multiple component carriers.

  [0108] The UE 115-a may include a channel / interference estimation module 615-b, which performs the functions described above for the channel / interference estimation module 615 described with reference to FIGS. Can do. The UE 115-a may also include an RS reception control module 825 and a communication optimization module 830. The RS reception control module 825 may control aspects of the UE 115-a that perform channel estimation or interference estimation based on reception of RSs according to the RS density scheme for the UE 115-a. The RS density scheme may be selected based on the UE 115-a being an MTC device, a narrowband MTC device, etc., or otherwise operating as those devices, with an additional RS RE, There may be a higher density RS density scheme. The additional RS RE may provide increased channel estimation, interference estimation, and reporting opportunities to the UE 115-a.

  [0109] The communication optimization module 830 may provide improved communication functionality to the UE 115-a. For example, the communication optimization module 830 may determine the category of the UE 115-a, the category in which the UE 115-a is operating, or the RS density at which the UE 115-a supports the UE 115-a requirements for the base station 105. At least one of the communication parameters for allowing the selection of the scheme can be determined and reported.

  [0110] Memory 815 may include random access memory (RAM) and read only memory (ROM). Memory 815, when executed, causes processor module 805 to perform various functions described herein (eg, perform channel estimation and reporting based on RS REs associated with RS density schemes, etc.). Computer readable computer executable software / firmware code 820 including instructions configured in Alternatively, computer readable computer executable software / firmware code 820 may not be directly executable by processor module 805, but may cause a computer to perform the functions described herein (eg, when compiled and executed). May be configured. The processor module 805 may include intelligent hardware devices, such as a central processing unit (CPU), microcontroller, application specific integrated circuit (ASIC), and the like.

  [0111] FIG. 9 shows a block diagram 900 of an apparatus 905 for use in wireless communications, in accordance with aspects of the present disclosure. In some examples, the device 905 may be the base station 105 described with reference to FIG. 1 or FIG. 3 or the source cell 205, 405, or 505 described with reference to FIG. 2, FIG. 4, and FIG. One or more of these may be examples of embodiments. In some examples, apparatus 905 may be part or include an LTE / LTE-A eNB and / or an LTE / LTE-A base station. The device 905 may be a processor. Apparatus 905 may include a receiver module 910, an RS density scheme module 915, and a transmitter module 920. Each of these modules may be in communication with each other.

  [0112] The components of apparatus 905 may be implemented individually or collectively using one or more ASICs adapted to perform some or all of the functions applicable in hardware. . Additionally or alternatively, the functions may be performed by one or more other processing units (or cores) on one or more integrated circuits. In other examples, other types of integrated circuits (eg, structured / platform ASIC, FPGA, and other semi-custom ICs) that can be programmed in any manner known in the art may be used. The functionality of each component may also be implemented in whole or in part by instructions embodied in memory formatted to be executed by one or more general purpose or special purpose processors.

  [0113] In some examples, the receiver module 910 includes at least one such as an RF receiver operable to receive from the UE 115 at least one of a channel estimate or interference estimate report signal associated with the device 905. One radio frequency (RF) receiver may be included. Receiver module 910 can transmit various types of data or control signals over one or more communication links of a wireless communication system, such as one or more communication links of wireless communication system 100 described with reference to FIG. Can be used to receive (eg, send).

  [0114] In some examples, the transmitter module 920 includes at least one RF transmission, such as at least one RF transmitter operable to transmit RS, eg, CRS, DM-RS, or combinations thereof. May include a machine. The transmitter module 920 may transmit various types of data and / or data via one or more communication links of a wireless communication system, such as one or more communication links of the wireless communication system 100 described with reference to FIG. It can be used to transmit a control signal (eg, transmission). The transmitter module 920 may be configured to transmit the RS by a unicast or broadcast channel type and may be configured to transmit via a control channel type or data channel type, such as a PDCCH or PDSCH channel type.

  [0115] In some examples, the RS density scheme module 915 may select an RS density scheme from a set of RS density schemes available for RS transmission. The selection of the RS density scheme may be associated with the port count of apparatus 905 in some examples, parameters associated with the channel, mobile device category of UE 115 that receives the RS transmission, or mobile device of UE 115 that receives the RS transmission. It may be based at least in part on any one or more of the capabilities. For example, the RS density scheme module 915 identifies any one or more of a UE category, a category in which the UE 115 is otherwise operating, or a port count and can use the RS density scheme for selection Select from a set of different RS density schemes. A set of available RS density schemes may include higher density RS density schemes that provide UE 115 with additional channel estimation and measurement opportunities or interference estimation and measurement opportunities. The RS density scheme module 915 may transmit the RS to the UE 115 via the transmitter module 920 according to the determined RS density scheme. In some examples, the transmission of RS may include one or more of CRS or DM-RS or a combination thereof. The RS density scheme module 915 may send an indication of the RS density scheme to the UE 115.

  [0116] FIG. 10 shows a block diagram 1000 of an apparatus 905-a for use in wireless communications, in accordance with aspects of the present disclosure. In some examples, the device 905-a may include the base station 105 described with reference to FIGS. 1 and 3, the source cell 205, 405, or 505 described with reference to FIG. 2, FIG. 4, and FIG. Or an example of one or more of the devices 905 described with reference to FIG. In some examples, apparatus 905-a may be part or include an LTE / LTE-A eNB or an LTE / LTE-A base station. The device 905-a may be a processor. Apparatus 905-a may include a receiver module 910-a, an RS density scheme module 915-a, and / or a transmitter module 920-a. Each of these modules may be in communication with each other.

  [0117] The components of apparatus 905-a may be implemented individually or collectively using one or more ASICs adapted to perform some or all of the functions applicable in hardware. Can be done. Additionally or alternatively, the functions may be performed by one or more other processing units (or cores) on one or more integrated circuits. In other examples, other types of integrated circuits (eg, structured / platform ASIC, FPGA, and other semi-custom ICs) that can be programmed in any manner known in the art may be used. The functionality of each component may also be implemented in whole or in part by instructions embodied in memory formatted to be executed by one or more general purpose or special purpose processors.

  [0118] In some examples, the receiver module 910-a may be an example of one or more aspects of the receiver module 910 described with reference to FIG. In some examples, the receiver module 910-a includes at least one of channel estimation or interference estimation, at least one RF receiver operable to receive an indication message from the UE 115, such as at least One radio frequency (RF) receiver may be included. Receiver module 910-a receives various types of data and data over one or more communication links of a wireless communication system, such as one or more communication links of wireless communication system 100 described with reference to FIG. / Or may be used to receive control signals (eg, transmissions).

  [0119] In some examples, transmitter module 920-a may be an example of one or more aspects of transmitter module 920 described with reference to FIG. In some examples, transmitter module 920-a may include at least one RF transmitter, such as at least one RF transmitter operable to transmit RSs in the RE according to a selected RS density scheme. . The transmitter module 920-a may transmit various types of data and data via one or more communication links of the wireless communication system, such as one or more communication links of the wireless communication system 100 described with reference to FIG. And / or may be used to transmit control signals (ie, transmissions). The transmitter module 920-a may be configured to transmit RS by unicast or broadcast channel type, via a control channel type or data channel type, which may be a PDCCH or PDSCH channel type in some examples. It may be configured to transmit.

  [0120] In some examples, the RS density scheme module 915-a may include a mobile device category / capability identification module 1005, a channel parameter identification module 1010, and an RS density scheme selection module 1015. The RS density scheme selection module 1015 may include a channel / interference estimation selection module 1020. Mobile device category / capability identification module 1005 may identify at least one of a category associated with the mobile device or a category in which the mobile device is operating in another manner. The mobile device category may be an MTC device, a narrowband MTC device, a narrowband UE, or a combination thereof. In some examples, the mobile device category is category 0.

  [0121] In some aspects, the mobile device category / capability identification module 1005 may identify a coverage extension for the mobile device and select an RS density scheme based at least in part on the identified coverage extension. For example, mobile device category / capability identification module 1005 may receive a message from the mobile device indicating operational capabilities for the mobile device via receiver module 910-a. The operational capability is that the mobile device can benefit from the improved coverage area provided by device 905-a, eg, 10 dB, 15dB, 20dB, etc. of coverage provided by device 905-a. May include indications. A higher density RS density scheme may be selected to provide channel estimation to support extended coverage.

  [0122] In some aspects, the mobile device category / capability identification module 1005 may identify a transmission mode for the mobile device and select an RS density scheme based at least in part on the identified transmission mode. For example, the transmission mode may be a broadcast transmission mode, and the selected RS density scheme may be a higher density RS density scheme with more RS REs in the PRB / subframe. In contrast, a unicast transmission mode may include selecting a lower density RS density scheme that includes fewer RS REs.

  [0123] The channel parameter identification module 1010, in some examples, may determine which antenna ports are available to the device 905-a to transmit the RS. For example, the device 905-a may include or otherwise have available 1 port, 2 port, 3 port, etc. for transmitting the RS. The available antenna port may determine the port count for device 905-a.

  [0124] The RS density scheme selection module 1015 may select an RS density scheme from a set of RS density schemes available for RS transmission. The RS density scheme may be selected based on one or more parameters associated with the channel, a mobile device category associated with the mobile device, and / or a mobile device capability associated with the mobile device. The set of RS density schemes may include a relatively low density RS density scheme and a relatively high density RS density scheme. A higher density RS density scheme may include more RS REs than a lower density RS density scheme. In some examples, the higher density RS density scheme is backward compatible with the lower density RS density scheme, eg, at least the same RS density scheme as the lower density RS density scheme in addition to the new RS RE. It may contain RE. The selected RS density scheme may include a cell specific reference signal (CRS) or a demodulated reference signal (DM-RS) or a combination thereof being transmitted to one or more mobile devices.

  [0125] In some aspects, the RS density scheme selection module 1015 increases the number of RSs transmitted to the mobile device based at least in part on the identified mobile device category or mobile device capability of the mobile device. Can include. For example, an RS density scheme may include 20 RS REs in a subframe.

  [0126] In some aspects, the RS density scheme selection module 1015 may transmit a message including an indication of the selected RS density scheme to the mobile device via the transmitter module 920-a. For example, the message may be a DCI element in the control channel that is sent to the mobile device. The message may also include an indication of whether DM-RS is included in the selected RS density scheme.

  [0127] Channel / interference estimation selection module 1020 may determine at least one of channel estimation requirements or interference estimation requirements that may be used to select an RS density scheme. In some examples, channel / interference estimation selection module 1020 may receive a channel quality indication based on the transmitted reference signal from the mobile device. Channel / interference, depending on any one or more of the UE's mobile device category, UE's mobile device capabilities, port count, etc., one or more parameters associated with the channel, UE's communication mode, etc. The estimation selection module 1020 may determine and output information indicating that additional channel estimation, interference estimation, or reporting may be sought, and thus a higher density RS density scheme may be selected. In some examples, the channel / interference estimation selection module 1020 may select a selected RS density scheme based on channel feedback from the mobile device, reception of one or more negative acknowledgment (NACK) signals from the mobile device, etc. Can affect.

  [0128] FIG. 11 shows a block diagram 1100 of a base station 105-a (eg, a base station that forms part or all of an eNB) for use in wireless communications, according to aspects of this disclosure. In some examples, the base station 105-a may include the base station 105 described with reference to FIGS. 1, 3, and 11, and the source cell 205 described with reference to FIG. 2, FIG. 4, and FIG. , 405, or 505, or one or more of the apparatus 905 described with reference to FIG. 9 or FIG. Base station 105-a may be configured to implement or facilitate at least some of the features and functions of the base station or apparatus described with reference to FIGS.

  [0129] Base station 105-a includes base station processor module 1110, base station memory module 1120, at least one base station transceiver module (represented by base station transceiver module 1150), and base station antenna 1155. At least one base station antenna and an RS density scheme module 915-b. Base station 105-a may also include one or more of base station communication module 1130 and / or network communication module 1140. Each of these modules may be in communication with each other directly or indirectly on one or more buses 1135.

  [0130] The base station memory module 1120 may include random access memory (RAM) or read only memory (ROM). Base station memory module 1120, when executed, causes base station processor module 1110 to perform various functions described herein for wireless communication (eg, port count, mobile device category, mobile device operation Computer-readable, computer-executable software / firmware code 1125 including instructions configured to cause an RS density scheme to be selected (eg, based on certain categories) may be stored. Alternatively, computer-readable, computer-executable software / firmware code 1125 may not be directly executable by base station processor module 1110 but is described herein (eg, when compiled and executed). The base station 105-b may be configured to perform various functions.

  [0131] Base station processor module 1110 may include intelligent hardware devices, such as a central processing unit (CPU), microcontroller, ASIC, and the like. Base station processor module 1110 may process information received through base station transceiver module 1150, base station communication module 1130, or network communication module 1140. Base station processor module 1110 may also communicate to transceiver module 1150 for transmission through antenna 1155 and to base station communication module 1130 for transmission to one or more other base stations 105-b and 105-c. Or may process information to be sent to the network communication module 1140 for transmission to the core network 1145, which may be an example of one or more aspects of the core network 130 described with reference to FIG. Base station processor module 1110 may handle various aspects of RS density scheme selection, and in some aspects, communication to mobile devices, either alone or in conjunction with RS density scheme module 915-b.

  [0132] Base station transceiver module 1150 modulates a packet, provides the modulated packet to base station antenna 1155 for transmission, and a modem configured to demodulate the packet received from base station antenna 1155. May be included. Base station transceiver module 1150 may be implemented in some examples as one or more base station transmitter modules and one or more separate base station receiver modules. Base station transceiver module 1150 may support communication in a first radio frequency spectrum band or a second radio frequency spectrum band. Base station transceiver module 1150 communicates bi-directionally with one or more UEs or devices, such as one or more of UEs 115 described with reference to FIGS. Can be configured. Base station 105 can include, for example, a plurality of base station antennas 1155 (eg, an antenna array). Base station 105 may communicate with core network 1145 through network communication module 1140. Base station 105-a may also communicate with other base stations, such as base stations 105-b and 105-c, using base station communication module 1130.

  [0133] The RS density scheme module 915-b is configured to implement or control some or all of the features or functions described with reference to FIGS. 1-10 in connection with RS density scheme selection. obtain. In some examples, the RS density scheme module 915-b identifies any one or more of a port count, a mobile device category, or a category in which the mobile device is operating and supports the mobile device. An RS density scheme may be selected from a set of available RS density schemes. For example, some mobile device categories may benefit from extra channel estimation opportunities, and a denser RS density scheme may be selected that has more RS REs per subframe. RS density scheme module 915-b, or portions of RS density scheme module 915-b may include a processor, or some or all of the functions of RS density scheme module 915-b may be performed by base station processor module 1110, Or it may be implemented with the base station processor module 1110. In some examples, the RS density scheme module 915-b may be an example of the RS density scheme module 915 or 915-a described with reference to FIG. 9 or FIG.

  [0134] In some examples, the RS density scheme module 915-b may include a channel / interference estimation control module 1160 and a mobile device category / capability control module 1165. The channel / interference estimation control module 1160 can determine channel estimation requirements or interference estimation requirements for the mobile device based on various factors, eg, the transmission mode of the mobile device, the coverage extension for the mobile device, etc. . Accordingly, the channel / interference estimation control module 1160 can determine whether additional RS REs can be provided to support the added channel estimation or interference estimation opportunities in the selected RS density scheme.

  [0135] In some examples, the mobile device category / capability control module 1165 may indicate to which mobile device category a mobile device such as, for example, an MTC device, a narrowband MTC device, a narrowband UE, a category 0 UE, is associated, Or it can be determined in which category it is operating in a different way. Accordingly, the mobile device category / capability control module 1165 determines an RS density scheme that provides sufficient channel estimation or interference estimation opportunities to support the mobile device based at least in part on the mobile device category or mobile device capability. do it.

  [0136] FIG. 12 is a flowchart illustrating a method 1200 for wireless communication in accordance with aspects of the present disclosure. For clarity, the method 1200 is described with respect to the base station 105 described with reference to FIGS. 1, 3, and 11 and the source cells 205, 405, and 505 described with reference to FIG. 2, FIG. 4, or FIG. And / or one or more of the devices 905 described with reference to FIG. 9 or FIG. In some examples, the base station may execute one or more sets of codes to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station can perform one or more of the functions described below using special purpose hardware.

  [0137] At block 1205, the method 1200 may include identifying a mobile device category or mobile device capability of the mobile device. For example, the mobile device may be a category 0 mobile device or may be operating in another manner as a category 0 device. In some examples, a mobile device may be associated with or otherwise operating as an MTC device, a narrowband MTC device, a narrowband UE, etc. In various examples, a mobile device category or mobile device capability may be associated with a mobile device that uses reduced communication functionality, eg, reduced data rate, narrow bandwidth, etc. The base station may determine the mobile device category independently or from the mobile device, eg, based at least in part on information received by a mobile device capability announcement message. The operations in block 1205 may be performed using any one or more of the RS density scheme modules 915 described with reference to FIG. 9, FIG. 10, or FIG.

  [0138] At block 1210, the method 1200 may include identifying one or more parameters associated with a channel for communicating a reference signal to the mobile device. In some examples, this may include identifying a port count available for sending RSs to the mobile device. The port count may be identified based on the configuration of the base station, eg, the number of antenna ports, and / or based on the available ports of the base station. In some examples, the port count may be one port, two ports, three ports, etc. The operation in block 1205 is described with reference to the RS density scheme module 915 described with reference to FIG. 9, FIG. 10, or FIG. 11, the channel parameter identification module 1010 described with reference to FIG. 10, or with reference to FIG. It may be implemented using any one or more of channel / interference estimation control module 1160.

  [0139] At block 1215, the method 1200 may include selecting an RS density scheme from a set of RS density schemes. For example, for each port count, the base station may have one or more RS density schemes available for RS transmission to the mobile device. The RS density scheme may be selected based at least in part on the mobile device category of the mobile device, or the mobile device capability of the mobile device. For example, a mobile device associated with a particular mobile device category or otherwise operating in that category may use a higher density RS density scheme that includes more RS REs per subframe. The additional RS RE may provide more channel measurement or interference measurement opportunities for the mobile device to improve channel estimation or interference estimation reporting. The operation in block 1205 is described with reference to the RS density scheme module 915 described with reference to FIG. 9, FIG. 10, or FIG. 11, the RS density scheme selection module 1015 described with reference to FIG. 10, or with reference to FIG. May be implemented using any one or more of the selected channel / interference estimation control modules 1160.

  [0140] At block 1220, the method 1200 may include transmitting an RS to the mobile device according to a selected RS density scheme. For example, the base station may transmit RSs in the RE according to a selected RS density scheme to provide sufficient channel measurements, interference measurements, and reporting opportunities. The operations in block 1205 are described with reference to the RS density scheme module 915 described with reference to FIG. 9, FIG. 10 or FIG. 11, the transmitter module 920 described with reference to FIG. 9 or FIG. It may be implemented using any one or more of the base station transceiver module 1150 or base station antenna 1155 described.

  [0141] In this manner, method 1200 may provide wireless communication. It should be noted that method 1200 is just one implementation, and that the operation of method 1200 can be reordered or otherwise modified as other implementations are possible.

  [0142] FIG. 13 is a flowchart illustrating a method 1300 for wireless communication according to various aspects of the disclosure. For clarity, the method 1300 includes the UE 115 described with reference to FIGS. 1, 3, and 11, the mobile devices 210, 410, and 510 described with reference to FIG. 2, FIG. 4, or FIG. / Or one or more of the devices 605 described with reference to FIG. 6 or FIG. In some examples, the UE may execute one or more sets of codes for controlling UE functional elements to perform the functions described below. Additionally or alternatively, the UE may perform one or more of the functions described below using special purpose hardware.

  [0143] At block 1305, the method 1300 may include receiving an RS transmitted according to an RS density scheme. The RS density scheme may be selected from a set of available RS density schemes. The RS density scheme may be selected based at least in part on a mobile device category associated with the UE, a mobile device capability associated with the UE in the channel, or one or more parameters associated with the channel. . The RS density scheme was a higher density RS density scheme (eg, with 20 RS REs per subframe) or a lower density RS scheme with fewer RS REs than a higher density RS scheme. It's okay. In some examples, receiving the reference signal may include receiving at least one of CRS or DM-RS or a combination thereof. The operations in block 1305 refer to the receiver module 610 described with reference to FIG. 6 or FIG. 7, the channel / interference estimation module 615 described with reference to FIG. 6, FIG. 7, or FIG. It may be implemented using any one or more of the transceiver modules 835 and antennas 840 described above.

  [0144] At block 1310, the method 1300 includes identifying an RS density scheme based at least in part on a type of channel associated with the reference signal or a coverage extension for the channel associated with the reference signal. obtain. In some examples, the channel type may be a broadcast channel or a unicast channel. In some examples, the channel type may be a control channel or a date channel, such as PDCCH or PDSCH. In some examples, the channel coverage extension may include channel repetition, and the RS density scheme may be identified based at least in part on the number of channel repetitions. Operation at block 1310 is performed by one or more of the channel / interference estimation module 615 described with reference to FIG. 6, FIG. 7, or FIG. 8, or the RS density scheme determination module 705 described with reference to FIG. May be implemented using.

  [0145] At block 1315, the method 1300 may include communicating using the reference signal according to the identified RS density scheme. Communicating may include performing at least one of channel estimation or interference estimation using the reference signal and transmitting an indication of channel estimation to the serving base station. Thus, the serving base station can adjust the transmission to take into account channel conditions and support UE communication. The operation in block 1315 is performed with reference to the channel / interference estimation module 615 described with reference to FIG. 6, FIG. 7 or FIG. 8, the channel / interference estimation determination module 710 described with reference to FIG. One or more of the described coverage extension / transmission mode module 715, the transmitter module 620 described with reference to FIG. 6, or the transceiver module 835 and antenna 840 described with reference to FIG. May be implemented using

  [0146] In this manner, method 1300 may provide wireless communication. It should be noted that method 1300 is just one implementation and that the operation of method 1300 can be rearranged or otherwise modified as other implementations are possible.

  [0147] FIG. 14 is a flowchart illustrating a method 1400 for wireless communication according to various aspects of the disclosure. For clarity, the method 1400 is described with respect to the base station 105 described with reference to FIGS. 1, 3, and 11, the source cell 205, 405, or 505 described with reference to FIG. 2, FIG. 4, or FIG. And / or one or more of the devices 905 described with reference to FIG. 9 or FIG. In some examples, the base station may execute one or more sets of codes to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station can perform one or more of the functions described below using special purpose hardware.

  [0148] At block 1405, the method 1400 may include identifying a mobile device category or mobile device capability of the mobile device. The mobile device may be a category 0 mobile device or may be operating in another manner as a category 0 mobile device. In some examples, the mobile device may belong to or otherwise operate as an MTC device, a narrowband MTC device, a narrowband UE, and the like. In other examples, a mobile device category or mobile device capability may be associated with a mobile device that uses reduced communication functionality, eg, reduced data rate, narrow bandwidth, etc. The base station may determine the mobile device category or mobile device capability independently or from the mobile device, eg, based on information received by a mobile device capability announcement message.

  [0149] At block 1410, the method 1400 may include identifying one or more parameters associated with the channel. In some examples, the method may include identifying a port count for communicating the RS to the mobile device. The port count may be identified based at least in part on the configuration of the base station, eg, the number of antenna ports, and / or available ports of the base station. In some examples, the port count may be one port, two ports, three ports, etc.

  [0150] At block 1415, the method 1400 may provide a higher density based at least in part on any one or more of the UE port count, the UE category, or the category in which the UE is operating. Determining whether a particular RS scheme should be selected. For example, the RS density scheme may be selected from a set of RS density schemes associated with a port count, UE category, or UE capability. In one example, a higher density RS density scheme is where the UE is an MTC device or otherwise operating as an MTC device, a narrowband MTC device, a UE operating in a narrowband, It may be selected such as when the UE supports multiple RS density schemes. If it is determined that a higher density RS density scheme should be selected, the method 1400 may include selecting a higher density RS density scheme at block 1420.

  [0151] At block 1425, the method 1400 may include determining whether a higher density RS density scheme may be selected based at least in part on the coverage extension for the UE. For example, the base station may determine the UE based on the location of the UE (eg, at the cell boundary of the base station) and / or based on indications received from the UE indicating that coverage enhancement may be required. May be determined to be receiving problems (eg, based on receiving a predetermined number of NACK messages from the UE). The base station extends UE coverage by selecting a higher density RS density scheme to provide additional RS REs per subframe for added channel measurements, interference measurements, and reporting be able to. If a higher density RS density scheme is selected based on the coverage extension, method 1400 moves to block 1420 where a higher density RS scheme is selected.

  [0152] At block 1430, the method 1400 may include determining whether a denser RS density scheme should be selected based on the transmission mode of the UE. For example, the base station can determine that the UE is engaged in broadcast communication, and thus a higher density RS density scheme can provide improved channel estimation, interference estimation, and reporting. The base station can provide improved broadcast transmission coverage based on the added channel estimation or interference estimation reports.

  [0153] If a higher density RS density scheme is not selected, the method 1400 may move to block 1435, where a lower density RS scheme is selected. Lower density RS schemes may generally have fewer RS REs per subframe than higher density RS density schemes.

  [0154] The operations in blocks 1405, 1410, 1415, 1420, 1425, 1430 and / or 1435 are performed by any one of the RS density scheme modules 915 described with reference to FIG. 9, FIG. 10, or FIG. Multiple may be implemented.

  [0155] In this manner, method 1400 may provide wireless communication. Note that method 1400 is merely one implementation and that the operation of method 1400 can be rearranged or otherwise modified as other embodiments are possible.

  [0156] In some examples, aspects from two or more of the methods 1200, 1300, or 1400 may be combined. The methods 1200, 1300, and 1400 are merely exemplary implementations, and the operation of the methods 1200, 1300, or 1400 may be reordered or otherwise modified as other implementations are possible. Please note that.

  [0157] The techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms “system” and “network” are often used interchangeably. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA). CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Release 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, high-speed packet data (HRPD), and the like. UTRA includes wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as a global system for mobile communication (GSM (registered trademark)). The OFDMA system includes Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (WiFi (registered trademark), IEEE 802.16 (WiMAX (registered trademark)), Wireless technologies such as IEEE 802.20, Flash-OFDM (R) may be implemented. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) and LTE Advanced (LTE-A) are new releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). The techniques described herein may be used for the systems and radio technologies mentioned above, as well as other systems and radio technologies including cellular (eg, LTE) communications over unlicensed and / or shared bandwidth. However, in the above description, the LTE / LTE-A system is described as an example, and LTE terminology is used in most of the above description. However, the present technique is applicable to applications other than LTE / LTE-A application examples. .

  [0158] The detailed description set forth above with respect to the accompanying drawings describes examples and is not intended to represent the examples only, which may be implemented or fall within the scope of the claims. The terms “example” and “exemplary”, as used herein, mean “act as an example, instance, or illustration” and are “preferred” or “advantageous over other examples”. It doesn't mean that. The detailed description includes specific details for providing an understanding of the techniques described. However, these techniques can be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

  [0159] Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description are voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any of them Can be represented by a combination.

  [0160] Various exemplary blocks and components described with respect to this disclosure herein are general purpose processors, digital signal processors (DSPs), ASICs, field programmable gate arrays (FPGAs) or other programmable logic devices, individual It may be implemented or implemented using gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor is also implemented as a combination of computing devices, eg, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors associated with a DSP core, or any other such configuration. There is a case.

  [0161] The functionality described herein may be implemented in hardware, software executed by a processor, firmware, or a combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope and spirit of this disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or any combination thereof. Features that implement functions may also be physically located at various locations, including distributed states such that some of the functions are implemented at different physical locations. As used herein, including the claims, the word “and / or” when used in the listing of two or more items is any one of the listed items. Means that one can be employed alone, or any combination of two or more of the listed items can be employed. For example, if a composition is represented as containing components A, B, and / or C, the composition is A only, B only, C only, A and B combination, A and C combination, It may contain a combination of B and C or a combination of A, B and C. Also, as used herein, including the claims, an enumeration of items (eg, items ending in a phrase such as “at least one of” or “one or more of”). As used herein, "or" is an inclusive enumeration such that a phrase referring to "at least one of the item enumerations" refers to any combination of those items including a single member. Show. By way of example, “at least one of A, B, or C” refers to A, B, C, A-B, A-C, B-C, and A-B-C, and a plurality of the same elements. Any combination used (eg, AA AAA, AAB, AAC, ABB, ACC, BB, BBB) , B-B-C, C-C, and C-C-C, or any other sequence of A, B, and C).

  [0162] Computer-readable media includes both non-transitory computer storage media and communication media including any medium that enables transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer readable media can be RAM, ROM, electrically erasable programmable read only memory (EEPROM®), compact disk (CD) ROM or other optical disk storage, magnetic disk storage or Any other non-magnetic storage device or any other non-transitory device that may be used to carry or store the desired program code means in the form of instructions or data structures and accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor A temporary medium can be provided. Any connection is also properly termed a computer-readable medium. For example, software can be sent from a website, server or other remote source using coaxial technology, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, wireless, and microwave. Wireless technologies such as coaxial cable, fiber optic cable, twisted pair, DSL, or infrared, radio, and microwave are included in the definition of media. Discs and discs used in this specification are CD, laser disc (registered trademark), optical disc (disc), digital versatile disc (DVD), floppy (registered trademark). Discs and Blu-ray® discs, which typically reproduce data magnetically, and the disc optically reproduces data with a laser . Combinations of the above are also included within the scope of computer-readable media.

  [0163] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Thus, the present disclosure should not be limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (30)

A method for wireless communication,
Receiving a reference signal transmitted according to a reference signal (RS) density scheme, wherein the RS density scheme is selected from a set of RS density schemes;
Identifying the RS density scheme based at least in part on a type of channel associated with the reference signal or a coverage extension for the channel associated with the reference signal;
Communicating with the reference signal according to the RS density scheme. Receiving an indication of an RS density scheme, wherein the RS density scheme is identified based at least in part on the indication, the indication being received in dedicated signaling or broadcast information;
The method of claim 1. Receiving the reference signal comprises:
Receiving at least one of a cell specific reference signal (CRS) or a demodulated reference signal (DM-RS) or a combination thereof,
The method of claim 1. Receiving a set of reference signals according to the RS density scheme and based at least in part on one of a mobile device category or mobile device capability;
The method of claim 1. The mobile device category or the mobile device capability is at least one of a machine type communication (MTC) device, a narrowband MTC device, a user equipment (UE) operating in a narrowband, or a UE that supports multiple RS density schemes. With one,
The method of claim 4. The RS density scheme is further determined based on one or more parameters associated with the channel.
The method of claim 1. The type of the channel associated with the reference signal comprises at least one of a broadcast channel or a unicast channel;
The method of claim 1. The type of the channel associated with the reference signal comprises at least one of a control channel or a data channel;
The method of claim 1. The coverage extension of the channel comprises repetition of the channel, and the RS density scheme is identified based at least in part on the number of repetitions of the channel;
The method of claim 1. The RS density scheme is identified for a first iteration number, another RS density scheme is identified for a second iteration number that is greater than the first iteration number, and the another RS density scheme is identified by the RS iteration number. Having a higher RS density than the density scheme;
The method of claim 9. Communicating using the reference signal
Performing at least one of channel estimation or interference estimation using the reference signal;
The method of claim 1, comprising: decoding the channel based on the at least one of the channel estimate or the interference estimate. A device for wireless communication,
Means for receiving a reference signal transmitted according to a reference signal (RS) density scheme, wherein the RS density scheme is selected from a set of RS density schemes;
Means for identifying the RS density scheme based at least in part on a type of channel associated with the reference signal or a coverage extension for the channel associated with the reference signal;
Means for communicating using the reference signal according to the RS density scheme. Means for receiving an indication of an RS density scheme, the RS density scheme being identified based at least in part on the indication, wherein the indication is received in dedicated signaling or broadcast information The
The apparatus according to claim 12. The means for receiving the reference signal comprises:
Means for receiving at least one of cell specific reference signal (CRS) or demodulated reference signal (DM-RS) or a combination thereof;
The apparatus according to claim 12. Means for receiving a set of reference signals according to the RS density scheme and based at least in part on one of a mobile device category or mobile device capability;
The apparatus according to claim 12. The mobile device category or the mobile device capability is at least one of a machine type communication (MTC) device, a narrowband MTC device, a user equipment (UE) operating in a narrowband, or a UE that supports multiple RS density schemes. With one,
The apparatus according to claim 15. The means for identifying the RS density scheme is operable based at least in part on one or more parameters associated with the channel;
The apparatus according to claim 12. The type of the channel associated with the reference signal comprises at least one of a broadcast channel or a unicast channel;
The apparatus according to claim 12. The type of the channel associated with the reference signal comprises at least one of a control channel or a data channel;
The apparatus according to claim 12. The coverage extension of the channel comprises repetition of the channel, and the RS density scheme is identified based at least in part on the number of repetitions of the channel;
The apparatus according to claim 12. The means for identifying the RS density scheme is operable to identify the RS density scheme for a first iteration number, and for another second iteration number that is greater than the first iteration number. Identifying an RS density scheme, wherein said another RS density scheme has a higher RS density than said RS density scheme;
The apparatus of claim 20. The means for communicating using the reference signal comprises:
Means for performing channel estimation using the reference signal;
13. The apparatus of claim 12, comprising: means for transmitting the channel estimation indication to a serving base station. A device for wireless communication,
A processor;
Memory in electronic communication with the processor;
Instructions stored in the memory, wherein the instructions are sent to the device by the processor,
Receiving a reference signal transmitted according to a reference signal (RS) density scheme, wherein the RS density scheme is selected from a set of RS density schemes;
Identifying the RS density scheme based at least in part on a type of channel associated with the reference signal or a coverage extension for the channel associated with the reference signal;
An apparatus capable of performing communication using the reference signal according to the RS density scheme. The instructions are sent to the device by the processor.
Executable to cause an indication of an RS density scheme to be received, the RS density scheme being identified based at least in part on the indication, wherein the indication is received in dedicated signaling or broadcast information The
24. The device of claim 23. The instructions are sent to the device by the processor.
Executable to receive at least one of cell specific reference signal (CRS) or demodulated reference signal (DM-RS) or a combination thereof;
24. The device of claim 23. The instructions are sent to the device by the processor.
Executable to cause a set of reference signals to be received according to the RS density scheme and based at least in part on a mobile device category or mobile device capability;
24. The device of claim 23. The type of the channel associated with the reference signal comprises at least one of a broadcast channel or a unicast channel;
24. The device of claim 23.   24. The apparatus of claim 23, wherein the type of the channel associated with the reference signal comprises at least one of a control channel or a data channel. The instructions are sent to the device by the processor.
Using the reference signal to perform at least one of channel estimation or interference estimation;
Executable to cause the channel to be decoded based on at least one of the channel estimate or the interference estimate;
24. The device of claim 23. A non-transitory computer readable medium storing computer executable code for wireless communication, the code comprising:
Receiving a reference signal transmitted according to a reference signal (RS) density scheme, wherein the RS density scheme is selected from a set of RS density schemes;
Identifying the RS density scheme based at least in part on a type of channel or a coverage extension for the channel;
A non-transitory computer readable medium executable to communicate with the reference signal according to the RS density scheme.

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